Growth of epitaxial ZnO films on Si(111)
- PDF / 297,287 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 75 Downloads / 244 Views
Growth of epitaxial ZnO films on Si(111) Chunming Jin, Ashutosh Tiwari, A. Kvit and J. Narayan Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695-7916
ABSTRACT Epitaxial ZnO films have been grown on Si(111) substrates by employing a AlN buffer layer during a pulsed laser-deposition process. The epitaxial structure of AlN on Si(111) substrate provides a template for ZnO growth. The resultant films are evaluated by transmission electron microscopy, x-ray diffraction, and electrical measurements. The results of x-ray diffraction and electron microscopy on these films clearly show the epitaxial growth of ZnO films with an orientational relationship of ZnO[0001]||Aln[0001]||Si[111] along the growth direction and ZnO[211 0]||AlN[211 0]||Si[011] along the in-plane direction. High electrical conductivity (103 S/m at 300 K) and a linear I-V characteristics make these epitaxial films ideal for microelectronic, optoelectronic, and transparent conducting oxide applications.
INTRODUCTION The need for blue and ultraviolet light emitting diodes and lasers has provoked enormous scientific and technological interest in II-VI and III-V wide band-gap semiconductors1-5. ZnO (bandgap of 3.27 eV at 300K) in II-VI semiconductor family1,2 compares very favorably with GaN of III-V systems with almost identical bandgap and some additional advantages. To vary the bandgap of ZnO, it can be alloyed with MgO(8.2 eV) to increase the bandgap or with CdO(2.0 eV) to decrease it. This is similar to III-nitride system, where GaN is alloyed with AlN (6.2 eV) to increase the bandgap or with InN (1.8 eV) to decrease it. ZnO has a exciton binding energy of 60 meV compared to 25 meV for GaN, higher exciton binding energy results in less trapping of carriers and higher luminiscent efficiencies2. In addition to above, transition metal atoms(Mn, V, Fe, Co etc.) doped ZnO is a candidate of dilute magnetic semiconductors (DMS) that can be used as spintronic materials4-7. ZnO has a wurtzite structure with lattice constant of a=3.2498Å and c=5.2066Å. ZnO thin films have been grown by using several different techniques including pulsed laser deposition (PLD), plasma-assisted molecular beam epitaxy etc. It has been reported that ZnO thin films can be epitaxially grown on the (0001) oriented sapphire (α-Al2O3) substrate with a domain epitaxy growth mechanism (sapphire has a hexagonal structure of lattice constant of a=4.758Å and c=12.991Å). However, for the practical applications, the integration of ZnO thin films with Si substrate is more desirable. In this paper, we report the epitaxial growth of ZnO thin films on Si(111) substrate with AlN as a buffer layer by using pulsed laser deposition technique. AlN has hexagonal wurtzite structure with lattice constants of a=3.112 Å and K10.7.1 Downloaded from https://www.cambridge.org/core. University of Arizona, on 27 Jul 2018 at 06:55:08, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1557/PROC-722-
Data Loading...
